If you discover brown mushrooms on your lawn, you don’t necessarily have to do something about it. Because many mushrooms with their breakdown products ensure good soil quality. However, sometimes the mushrooms are poisonous, so it’s important to collect the mushrooms and take a few steps to prevent re-infestation. As a rule, the mushrooms require certain site conditions so that they can grow. If you change the good cultivation conditions and strengthen the lawn, the fungi will no longer be able to survive over time. However, this does not happen overnight, but requires patience and perseverance.
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Mushrooms in the lawn – growth
Every gardener knows that fungi can cause disease in plants. But the invisible, lower fungi are mostly responsible for this. However, this is about the larger mushrooms with easily visible, brown or white fruiting bodies (stem with hat) that suddenly appear on the surface of the earth. Fungi are among the oldest organisms in the world. What we see in the lawn is not the fungus, but only its fruiting bodies, which are used for reproduction. In the soil, the actual fungus forms a dense network of long, strung together cells: the mycelium. This mycelium is usually located near the surface in the ground or another carrier medium such as rotting wood.
If the conditions are favorable for the fungus, i.e. moist and warm, it forms fruiting bodies, which then appear on the surface. Depending on the type of mushroom, this fruiting body can have different shapes and colors. The fruiting body only serves to multiply and spread the fungus. Mushrooms use two techniques to spread:
- the actual fungus in the soil (mycelium) opens up new areas
- the fruiting bodies form spores
The spores are extremely small and light, so that even the smallest air movements carry them away. The spores form in the lamellae on the underside of the hat (umbrella).
What conditions promote fungal growth?
Fungi do not have chlorophyll like plants that they can photosynthesize with to provide themselves with energy. Mushrooms have therefore specialized in utilizing organic carbon compounds produced by higher plants or animals. Most fungi only colonize dead tissue such as:
- dead leaves
- all Holz
- Remnants of lawn grasses (lawn thatch)
Lawn thatch consists of dead (or mown) blades of grass, dead roots and shoots of the grass. It offers an ideal breeding ground for mushrooms. Most mushrooms require moist site conditions. In this case, the thatch is ideal because it holds moisture well in the soil. Rotten plant residues offer the fungi the best conditions for optimal growth.
- moist soil that does not dry well
- partially shaded to shady location (sometimes full sun)
- rotten materials under or on the surface of the earth
Are fungi harmful to the lawn?
The vast majority of fungi have no influence whatsoever on living lawn grasses. Of these, the gardener only sees the fruiting body appear between the grasses for a short time once a year. Other types of fungi release substances such as nitrogen when the biomass is broken down. The nitrogen acts as a fertilizer on the lawn. Therefore, increased lawn growth can often be seen in the areas around the mushrooms. In summer, the fungal network in the soil can mean that the entire soil can no longer absorb the water sufficiently. In the worst case, the grasses on the lawn can die off when it is very dry.
Which mushrooms are you talking about?
Among the many types of mushrooms that can be found on a lawn, some are quite rare. There are common mushrooms, sometimes edible mushrooms, and some poisonous mushrooms that can grow on a lawn in good conditions.
- Fertilizer (Panaeolus): 15 species, mostly with a conical, brownish or greyish hat (1-1.5 cm wide) on a 6 to 10 cm long, fragile stem, poisonous
- Hallimasch (Armillaria): brownish to honey yellow hat, depending on the species 3 to 10 cm in diameter, grows on up to 20 cm long stalk, also colonizes living conifers, raw poisonous
- Poison hooding (Galerina marginata): brown hat up to 5 cm wide, flattened shape, stem with a white base, poisonous
- and many other types
If brown mushrooms appear on the lawn, the call to control them usually follows automatically. However, effectively eradicating mushrooms is not an easy endeavor. Chemical pesticides are generally not allowed against fungi, so the gardener often has no choice but to come to terms with them. As long as the fungus can easily grow, it usually poses no danger. It is only when they are consumed that they make them dangerous. This is especially critical when there are animals or small children on the lawn.
It is best to simply mow the lawn at short intervals when the fruiting bodies appear. In between, it is advisable to rake off the fruiting bodies with a fan rake. Gloves should be worn during removal in case of poisonous specimens. In addition, the leftovers must always be disposed of in the household waste so that the fungal spores do not spread on the compost.
Mushrooms need moist soils. The infestation is particularly favored by a water build-up in the soil. It is important that the lawn can always dry well after it has rained or when dew forms on cool days. If the grass clippings are not removed or only insufficiently removed during mowing, this prevents the water from evaporating. If the location is naturally very moist and the soil is heavy, optimal conditions are created for a fungal attack.
Avoid anything in the lawn that promotes the formation of thatch. The thin layer of dead stalks and cut grass encourages the fungus to grow in the soil. If the lawn thatch is already there, it must be removed. This deprives the fungus of its nutritional basis. If the drought lasts for a long time, the lawn should be watered regularly. This not only keeps the grass viable, but also the bacteria in the soil that break down the felt.
In order to remove strong matting of the lawn and to prevent new matting, the lawn should be scarified several times a year as required. When scarifying, the dead grass and old lawn clippings are cut vertically with the help of rotating knives and then removed. The growth of grasses is most pronounced between April and June, so scarifying should be done more often, especially in these months.
Aeration and sanding
A good permeability of the sod for water is necessary for good lawn growth. At the same time, these conditions are unfavorable for the growth of the fungus. Above all, frequent stress on the lawn from playing children or other steps compact the soil and make it prone to waterlogging. This compression makes mechanical measures necessary. During aeration, fine holes are made in the ground with the help of hollow spikes. Thin earth cores about five to seven centimeters deep are cut out, which remain on the lawn surface. In a second step, this earth must then be removed. In practice, it makes sense to carry out this measure about twice a year. The resulting holes are filled with sand for better drainage.
Remove dead wood
If there are dead roots or dead wood in the soil under the lawn, other pests in the soil can also trigger a fungal attack. In this case, you should search the areas that are infested with brown fungus for small holes in the ground. If you find what you are looking for, the ground must be dug up generously in order to find cavities where beetles, larvae or other pests reside. Mole crickets are often the actual cause of the fungal attack.
If moisture and vermin infestation can be ruled out for the many rotting plant remains, there may also be a lack of nutrients or adequate ventilation in the soil. Most plants cannot grow in very poor quality garden soil. Their roots slowly die off and form ideal conditions for a fungal attack. A deficiency symptom can often be recognized by the formation of so-called witch rings. The mushrooms are arranged in circles and the mushroom rings are lined with darker colored lawn. The lawn around the witch rings grows better than elsewhere because the fungi secrete certain nitrogen compounds (ammonium compounds) that act as fertilizers for the lawn. Around 50 different types of fungus can produce this damage.
- Dig out the soil around the mushroom nests
- remove the earth also in the immediate vicinity
- Remove any dead plant parts in the soil
- Fill holes with sandy humus
- Loosen the soil under the lawn
- sow new grass in the coming spring
The fruiting bodies of many mushrooms, such as the clove shrimp, often appear in a circular arrangement on the lawn. These circles can be up to several meters in size. In these places the grass grows much stronger in the lawn and is also darker in color. The cause of this are the mushrooms. They grow outward from their original location because they have used up their food supply. As the fungus spreads to all sides, the ring-shaped appearance is created. Every year the ring gets a little bigger. These mushroom rings are also called elf ring or fairy ring. Witch rings have already been found that are several kilometers in diameter and many hundreds of years old.
Brown mushrooms in the lawn may appear ugly, but in most cases they do not pose a threat to the lawn. Only in cases where animals or small children are there do they absolutely have to be removed. This works best with regular mowing and collecting. Fighting the fungus is very difficult because the parts that are visible are only the fruiting bodies. The actual mushroom is hidden in the ground as a mesh.